In 1949 a geologist named Vadim Kolpakov discovered a large mound of limestone in the north of the Irkutsk region in southeastern Siberia, about 360 km from the district center Bodaibo. The cone is curiously shaped with a crater at the top and a small mound in the center. The mound is about 40 meters high and 100 meters across at the base. The smaller mound at the top is about 12 meters high. The crater was named Patomskiy, after a nearby river, but local residents call it “the Fiery Eagle’s Nest”.

Since the discovery of the crater, there have been many theories as to what could have created it. For a long time it was believed to be a meteorite impact structure. Some linked it to the Tunguska meteorite, whose remains have never been discovered. But the crater does not resemble any other known meteorite site. Later, some geologists suggested that it could be a nascent volcano, but no volcanic material has ever been found either.